An international team of astronomers has identified evidence that six young red dwarfs swallowed rocky planets that formed around them. The signal came from the detection of lithium in their atmospheres. Pesquisadores from the universities of Keele and Exeter, at Reino Unido, analyzed data from spectroscopic observations. The finding was published in the journal Monthly Notices of the Royal Astronomical Society.
Red dwarfs are the most common stars in Via Láctea. Elas have a lower mass and temperature than Sol, but interiors hot enough to destroy lithium quickly by nuclear fusion. Therefore, the presence of this element in some of them attracted attention. The extra material would have come from rocky planets with masses between three and ten times that of Terra.
Análise of star clusters reveals chemical differences
Scientists used information from Gaia-ESO Spectroscopic Survey to study thousands of stars. Eles focused on three young open clusters: NGC 2451a, Blanco 1 and NGC 2516. In Nesses groups, the stars were born from the same material and at the same time, which facilitates comparisons. Seis red dwarfs stood out for having much greater amounts of lithium than their sisters of the same spectral type.
- NGC 2451a, Blanco 1 and NGC 2516 were the clusters analyzed
- Idades of the clusters range between 50 and 200 million years old
- Seis red dwarf stars showed excess lithium
- Comparação with stars from the same cluster confirmed anomaly
- Dados of Very Large Telescope and Gaia complemented the measurements
Comparison between coeval stars made it possible to isolate the effect. Normalmente, young red dwarfs would have already consumed all the lithium inherited from the original nebula. The observed excess points to the recent accretion of material rich in this element.
Lítio works as a planetary swallowing marker
Professor Robin Jeffries, from Universidade of Keele, led the work. Ele compared detecting lithium to throwing paint on a white canvas. The element stands out because it should not exist in measurable quantities in these stars. The most likely explanation is that the stars incorporated remains of rocky planets during the formation of their systems.
Estrelas absorb gas and dust as they form. However, rocky planets that get too close can be dismantled and swallowed. The lithium present in these bodies is not destroyed before reaching the star’s atmosphere. Esse mechanism explains the chemical imbalance observed in the six red dwarfs. Outras hypotheses, such as external contamination, were considered less likely given the data.
The phenomenon was predicted by theoretical models of planetary evolution. Agora, for the first time, direct observational evidence emerges on red dwarfs. Essas stars represent the vast majority of those in the galaxy. How Entender interacts with its planets helps refine predictions about the stability of planetary systems.
Implicações for planet formation around red dwarfs
The discovery suggests that planet swallowing may be common in the early stages. Most red dwarfs still preserve planets. Outras, however, may have lost part of their initial entourage. Isso has a direct impact on the search for habitable worlds. Regiões close to red dwarfs are priority targets in missions like the James Webb telescope.
Future Pesquisas should map more clusters. High-resolution Espectrógrafos will allow you to check whether the pattern repeats itself. Modelos computational devices can also simulate the dynamics that lead to the dive of planets into the star. The British team plans to continue analyzing data from Gaia and other surveys.
Detalhes spectroscopic observation technicians
Gaia-ESO Survey provided detailed spectra of more than 100,000 stars. The technique measures light intensity at different wavelengths. Specific absorption Linhas reveal the presence and amount of lithium. The six red dwarfs stood out even when compared to stars of similar mass and age within the same cluster.
The clusters studied are at distances that allow accurate observations from the ground. NGC 2516, for example, is one of the closest and best studied. The combination of data from the VLT, ESO, and the Gaia satellite gave precision to measurements of chemical composition and movement. Isso reinforces the reliability of the results.